1. Field of the Invention
This invention relates to cameras having an information mark display device and, more particularly, to the finder display of camera in which undesirable light is removed.
2. Description of the Related Art
In this kind of device, many methods have been proposed. For example, LEDs or like display elements are put in a portion of the space surrounding the pentagonal roof type prism, and light issuing from them is brought by transmission to the finder viewing area (Japanese Utility Model Publication No. Sho 62-41311). In another method, a diffraction grating is formed on the focusing screen. The LEDs are positioned to face one side of the focusing screen so that light issuing from them is conducted by total reflection to the diffraction grating, by which it is bent to the finder viewing area (Japanese Laid-Open Patent Application No. Sho 56-99332). However, these are to present the display outside the field of observation.
Therefore, as the display is illuminated by the light emitting element disposed on the side of the pentagonal prism, the length of optical path has to be corrected at the outside of the pentagonal prism so that the distance from the display to the eye is equal to the distance from the focusing screen to the eye. This causes the layout to be complicated and its scale to greatly increase. A different example from those described above is shown in U.S. Pat. No. 4,662,716 where the display is made to be presented in superimposing relation on the scene image. But, this has a problem of dimming the display.
In addition, in U.S. patent application Ser. No. 480,671 filed on Feb. 15, 1990 which issued as U.S. Pat. No. 5,053,803 on Oct. 1, 1991 there is proposed a device for displaying an image of characters in the field of observation in such a way that the characters in the form of minute refractors positioned at or near a predetermined focal plane of the image forming lens are selectively illuminated by the light reflected from the main mirror.